Device comprising a current converting tube



J. G. W. MULDER DEVICE COMPRISING A GURRENT CONVERIING TUBE Filed July20, 1946 Jan. 18, 1949.

3 Sheets-Sheet 1 AGEN Jan. 18, 1949. 4 5, w, MULDER 2,459,284

DEVIC E COMPRISING A CURRENT CONVERTING TUBE Filed July 20, 1946 3Sheets-Sheef 2 AGENT Jan. 18, 1949. w MULDER 2 459,284

DEVICE COMPRISING A CURRENT CONVERTING TUBE Filed July 20 1946 3Sheets-Sheet 5 AGENT Patented Jan. 18, 1949 DEVICE COMPRISING A CURRENTCONVERTING TUBE Johannes Gijsbertus Wilhelm Mulder, Eindhoven,Netherlancls, assignor to Hartford National Bank and Trust Company,Hartford, Conn., as

trustee Applieation July 20, 1946, Serial N0. 685,208 In the NetherlandsJ anuary 30, 1943 3 Claims.

This invention relates to a device comprising a current converoing tubehaving a filling of gas 01 of vapour er of both, in Which acathodescreen is provided between the cathode and one or more anode.

These tubes often have the dravvback that the first ignition voltagerequired when placing the tube into service, largely depends on thetemperature. When, for instance, just afcer the operation the tube ispractically still at its operating temperature, the first ignitionvoltage required on operating the tube anew is very high. When as aresult of screens placed between the cathode and the anode the dischargehas to follow complicated paths the requirement of an increased ignitionvoltage in the case of a high temperature f the tube is particularlymanifest.

Tubes that are so constructed as to be free from arcing back ab the fulloperating voltage and at every cathode temperature 1ower than the normal(Application for a. patent Serial N0. 731,289, fi1ed February 27, 1947,now Patent 2452861 issued November 2, 1948) switched on simultaneouslyWith the heating current.

lt is a1ready known to connect a screen, which is placed between cathodeand anode, to one of he anodes through a resistance. This, however, hasthe dravvback of the full voltage being set up between this screen andthe cahode in the negative phase, which may involve a very strengglowing current between these electrodes.

The present invention purports to eure these drawbacks by connecting thecathode screen of the tube so a potentiometer or voltage-dividerconnected between the cathode and one of the anodes. The current fromthe cathode to the screen ionizes the gas at a comparatively W voltagewhich depends on the filling of the taube. Once the curre-nt from thecathode to the screen has ionized ehe gas medium, charge carriersreadi1y enter the range of the anode fie1d in substantia1 quantity. Inpractice the paths of the gaseous medium so the screen and anode areionized simultaneously. The choice of the point of a voltage-divider,where the ca.thode screen is connected, determines the anode voltage atWhich ionization occurs. Of course, the resistance 01 thevoltage-divider between the anode and. the screen should not be too 10Win order 170 .prevent an unduiy strong glow discharge between cathodeand screen in the negative phase.

Although, once the taube gas medium has ionized anal conveys a 1ittlecurrent, re-ignition takes place very easily tubes having two and moreanodes suffer from the drawback that the comdiions of re-ignition arenot the same for all anodes, due 130 the fact that the cathode screen isconnected between one of the anodes terminals anc1 the cathode. In thiscase 113 is particu larly advantageous to connecb a certain number ofparts of the cathode screen corresponding so i-he number of anodes tothe Voltag'e divided con nected between tne cathode and each anode.

It is particularly advantageous t0 use the in" vention in tubes for morethan volts effective anode voltage anal et least 10 amperes rec'cifiedcurrent, in which the screens between the cathode and the anodes areprovided in such a manner that at the ful1 operating voltage the tubedoes not exhibit, arcing back ab every cathode temperature lower thanEhe normal.

In a special form of construction of these tubes the cathode screen orparts thereof are provided With holes on the side facing the one or moreanodes, which holes do not serve for the passa.ge of the main dischargeanti therefore de not amount to more than 5% 0f the a.perture distantfor the last-mentioned discharge, in such a manner that particlesdisintegrating from the cathode cannot find their way to the anodes. Byproviding the ignition holes it ensured that charge carriers fro1'n thespace With the cathode screen can easily enter the rang'e of the anodefie1d between anode and screen.

In one form of construction of a tube Which particularly satisfies therequirement of freedom from arcing back, the terminal wires of the cathode and the one o1 more anodes a1e surrounded by tubes of ceramicmaterial which are fused together with the W311 of the tube, whereas theanodes, except for the active front surface, are surrounded by a screenconsisting of conducaive material, preferably meta1 ganze, which issecured to the tubes protecting the terminals. Betaveen the anodes isplaced a screen consisting cf meta1 she-et Whose rounded front side isc1osed to ehe cathode screen, the screens being arranged about thecathode in such manner that particles, for instance of electron-emittingmaterial, issuing from the cathode do not have a velocity compunent inthe direction of the anode even after a reflection.

The current converting tubes tha are the object of the present inventionoften have ab the bottom side a metal hood Icr taking up the stank 0fvapor-producing material, usually mercury. Sometimes the metal hood isadvantageousiy furnished With cooling ribs in order to maintain thetemperature cf the mercury as 10W es possible. It is particularly simpleanc1 cheap to mount ehe resistances of the voltage-divider on thecooling ribsso that the user of the t-ube need not bother abouttheseparts and may connect the tube in the same manner as tubes withoutcathode scr een or those where the cathode screen is internallyconnected to the cathode.

In order that the invention may be clearly understood anc1 readilycarried inbo. efiect it will now be described more fully with referencet o the accompanying drawing, given by wa.y of example.

Figures 1a, 1b anal 1c are of vertical section, a bottom view and ahorizontal section respectively of a tube having two ahndes in which thecathode screen is connected through a VON:- age-dividler to one of theanodes, Figu1es 2a 2b and 2c being respectively a, vertical anal ahorizontal section of the cathode screen of the tube, in which ehecathode screen is divided into two parts, and a bottom view of thistube.

The current converting taube shown in Figure 1 comprises a glassdischarge vessel l, in which the ca.thode 2 and the anodes 3 areprovidecl in the same way by means cf terminal wires 4 and 5 which,through the intermediary of chrome iron hoods 6 and i are sealed in avacuum-tight manner into Ehe ends of the tube. Bach anode is surroundedby a screen 8 partly consisting of meta1 gauge und. shielding theinactive part of the anocles. The terminal wires are surrounded by theceramic protecting tubes 9 and H3 which the cathode.

4 divider resistances niay be given diflerent ratio so thatthe.ionization occurs at a dififerent anode voltae.

In Figure 2 the parts corfesponding to Figure 1 bear the same referencenumeralg as in Figure l. In this case the cylindrical part of thecathode screen is divided into two parts 13' each of which correspondsto one of the two anodes and is secured to a terminal protecting tube ofThe two -ha1ves !3' slightly 0ver 1ap ea ch other so thas disturbanceson account of electron emitting material disintegrating frm th'ecachudeare avoided. The cov ar I4 of the cathode screen is separately securedto the insulating terminal tubes.

The tube inC1ud'es two inleas I5 for thetwo parts of the cathode screenand as further shown in Figure 2C two potentiometers each made up of aresistor pair 2 !22 are provided. The Voltagedivider is also constructeddouble and the chrome iron hood H is centrally positioned.

What I claim is:

l. A gaseous discharge current converting taube comprising a c1osedvesse1 haVing a gaseous filling, and containing a cathode, a pluralityof anodes, anal a cathorle screen mounted between the cathode anal theanodes, the cathode screen havin a number of 'sections corresponding tothe number of anoxies, a voltage-divider comnected between the cathodeand each anode, anal meai1s connecting each cathode screen section to anintermediate point of the corresponding voltage-divider between thecathode an d the asso- I ciated anode.

through the intermediary of a connecting wire 28. The T'WO cathodeinlet5 are furnished with copper connecting leads K6. Ab the bottom sideof the tube is provided a chrome iron hood IT containing the stock oImercury I8 which is protected by the screen 593 from the thermalradiation f1om he taube. The chrome iron hoocl H hag secured to it acooling rib 20 by Which it is ensured that the temperature of the mercury E3 on1y slig'htly exceeds room temperature. On the rib 22 aremounted two resistances 21 an. 22 jointly consticuting thevoltage-divider between the eathode and. one of the anodes. Theresistance 2! is directly electrically connected to the rib 22. Theresistance 22 is insulated from the rib 20 by meang cf two insulatingplates 23. A wire 241 connects the two resistances to the inlet 15 ofthe screen. The wires 26 and 27 are connected respectively tc the centref the hQJ* ing Winding of the supply for the device com- 2. A gaseousdischarge tube comprising a closecl vessel having a. gaseous filling,and containing a cathode and an anode, conducting supports f01 thecathode exaending through the wa1l ofthe Vessel and into the immer spacein the vessel,

insulating tubes covering the supports to substantially the termin'alsof the cathode a Cathode sCreen substanti'ally enclosing the cathode,means supporting the cathode screen onthe in sulating tubes andinsulated from Ehe cathode,

prising the currentconverting tube and 110 one of the anode terminals ofthe taube. The nuts 25 serve to secure the resistances and thecounecting wires. The, cathode screen is provided W1'th Tour ignitionho1es 29 by which the ignition of the anode current is facilitated.Besides a filling o1 mercury the tube also has a'filling of undp0tent-iometer resistance vmeans interconnecting said. anode, cathodeand cathode screen for maintaining the potential of the cathode screenat a value between the potentials of the cathode and of the anode.

3. A gaseoug dscharge current converting taube comprising a closedvessel having a gaseous fi11- ing, and containing a cathode an anode anda screen fr the cathode, a metallic cup secured in v the base of theBube td communicate With the tube, a globule of mercury in the cup heatradating ribs attached to the cup resist-ance means supported on seidribs, und an ele ctrical couductor extending through the base of thetaube With its inner end connected to thecathode screen and haVing ariexternal terminal fr counection a point 011 the resistance Ineans.

JOHANNES GIJSBERTUS WILHELM MULDER.

REFERENCES CITED The following references areof fecord in 1;he

file 0f this patent:

UNITED STA'I'ES PATENTS Number Na'me Date 1,038910 Von Lieben et.a1.Sept. 17, 1912 1426801 Wilson Aug. 22, 1922 1790153 Huil Jan. 27, 19312,-183918 Mulder Des. 19, 1939 2217185 Smith Oct. 8,1940

Certificate of Correction Patent N0. 2,459,284. January 18, 1949.

JOHANNES GIJSBERTUS WILHELM MULDER It is hereby certified that errorsappear in the printed specification 0f the above numbered patentrequiring correotion as follows:

Column 1, line 5, for the Word anode read anodes; line 23, after theparenthesis and before switched insert exhibz't a wem; grenzt dependencyof the z'gm'tirm voltage an the temperature. I n tkese tubes the amodevoltage mag; be line 40, for gas read gaseous; column 2, line 6, fordivided read dz'm'aler; column 3, line 27, for gauge read gauze; line69, f0r ionized read z'omlzes; and that the said Letters Patent shouldbe read with these corrections therein that the same may conform to therecord of the case in the Patent Ofiice.

Signed and sealed this 24th day of May, A. D. 1949.

THOMAS F. MURPHY,

Aaez'sta1zt ommz'ssz'oner of Patents.

